Devices and Methods for a Pyrolysis and Gasification System for Biomass Feedstock

ABSTRACT

A pyrolysis and gasification system and method convert a biomass feed stock to bio-char and synthesis gas. In one embodiment, the pyrolysis and gasification system includes a reactor for producing a synthesis gas and bio-char from a biomass feedstock. The system includes a flow measurement device and an air distribution system, which provides a fluidized bed in the reactor. The system also includes a cyclone assembly. The cyclone assembly removes the bio-char from the synthesis gas.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of biomass conversion and morespecifically to the field of devices and methods facilitating pyrolysisand gasification of biomass feedstock.

2. Background of the Invention

Methods for using energy from biomass have conventionally includedcombustion of the biomass with the heat energy used to produce steam.The steam may then be used to produce electric power. Drawbacks to suchconventional methods include slagging and fouling that occur withbiomass fuels containing low eutectic point (i.e., melting point) ash.For instance, the ash melts at relatively low temperatures and sticks tosurfaces, which may impact the sustainability of the thermal conversionsystem. Developments have included using bag filters to remove char byfiltration. For such developments, the gas temperature is cooled to atemperature at which the temperature of the gas is below the temperaturethat may result in damage to the bag filter media. Drawbacks to suchdevelopments include inefficiencies with the performance of the bagfilter for removing the smaller particulates. Additional drawbacksinclude inefficient methods for measuring the feed and removing char.Further drawbacks include inefficient methods for fluidizing the bed.For instance, conventional methods use bubble caps or orifice plates.However, drawbacks to such conventional methods include pressure drop.

Consequently, there is a need for improved methods and devices forconversion of biomass.

BRIEF SUMMARY OF SOME OF THE PREFERRED EMBODIMENTS

These and other needs in the art are addressed in one embodiment by anair distribution system for a reactor, wherein bed materials aredisposed in the reactor. The air distribution system includes an airdistribution plate. In addition, the air distribution system has aplurality of air distributors. The plurality of air distributors areattached to the air distribution plate. Each of the air distributors hasa base and a distribution arm. The distribution arm has distributororifices. The distribution arm is disposed about parallel to the airdistribution plate. Moreover, the distribution arm has a bottom side.The distributor orifices are disposed on the bottom side of thedistribution arm.

These and other needs in the art are addressed in another embodiment bya flow measurement device adapted for measuring biomass flow. The flowmeasurement device includes a plurality of feed rollers. Each of thefeed rollers is rotatable. In addition, each feed roller has a rollershaft and roller blades. The flow measurement device is calibrated toallow determination of the biomass flow from rotation of the feedrollers.

In addition, these and other needs in the art are addressed in anembodiment by a cyclone assembly for removing char from a gas producedfrom a biomass feedstock. The cyclone assembly includes a first cyclone.The first cyclone is a low energy cyclone. The cyclone assembly alsoincludes a second cyclone. The second cyclone is a high efficiencycyclone. The first cyclone is disposed to receive the gas. In addition,the gas exiting the first cyclone flows to the second cyclone.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter that form the subject of the claims of the invention Itshould be appreciated by those skilled in the art that the conceptionand the specific embodiments disclosed may be readily utilized as abasis for modifying or designing other embodiments for carrying out thesame purposes of the present invention. It should also be realized bythose skilled in the art that such equivalent embodiments do not departfrom the spirit and scope of the invention as set forth in the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of the preferred embodiments of theinvention, reference will now be made to the accompanying drawings inwhich:

FIG. 1 illustrates a side view of a pyrolysis and gasification system;

FIG. 2 illustrates a side perspective view of a flow measurement device;

FIG. 3 illustrates a side perspective view of a feed roller;

FIG. 4 illustrates a side perspective view of an air distributionsystem;

FIG. 5 a bottom view of an air distributor;

FIG. 6 illustrates a side perspective view of a first cyclone;

FIG. 7 illustrates a side perspective view of a second cyclone; and

FIG. 8 illustrates a side perspective view of a cyclone assembly.

DETAILED DESCRIPTION OF TIM PREFERRED EMBODIMENTS

FIG. 1 illustrates a side view of an embodiment of pyrolysis andgasification system 175 that includes feed hopper 180, reactor 185,cyclone assembly 140, and char collector 190. In an embodiment,pyrolysis and gasification system 175 produces bio-char and bio-oil froma biomass feedstock. The biomass feedstock may include any biomass. Forinstance, without limitation, examples of biomass feedstock includecotton gin trash, sorghum, sludge, straw, rye, and the like.

FIG. 2 illustrates a side perspective view of an embodiment of flowmeasurement device 5. Flow measurement device 5 includes metering device10 and feed rollers 15. Flow measurement device 5 is calibrated to allowthe amount of the biomass feedstock fed to pyrolysis and gasificationsystem 175 to be determined from the measured rotation of the feedrollers 15. Metering device 10 may include any suitable device forfacilitating determination of the amount of the biomass feedstock feed.In embodiments, a sensor (not illustrated) determines the amount of feedbased upon rotation of the metering devices 10. Flow measurement device5 may include any suitable number of metering devices 10 for determiningthe feedstock feed amount. In embodiments, each feed roller 15 has ametering device 10. In the embodiments as shown, each feed roller 15 hasa metering device 10 disposed on an end of the feed roller 15. As shownin the figure, each adjacent feed roller 15 has a metering device 10disposed on the same side of flow measurement device 5 as the adjacentfeed rollers 15.

As further shown in FIG. 2, embodiments of metering device 10 includemetering device body 30 and metering device ridges 35. Metering devicebody 30 may include any configuration suitable whereby rotation of feedroller 15 rotates the metering device body 30. In embodiments as shown,metering device body 30 is substantially circular. Metering deviceridges 35 are disposed about the outer edge 195 of metering device body30. In an embodiment as shown, metering device ridges 35 are raisedportions of outer edge 195. Each metering device ridge 35 extendscrosswise across outer edge 195 of metering device body 30.

A contact point 200 is disposed between each metering device ridge 35.It is to be understood that contact point 200 is the space between eachmetering device ridge 35. The metering device ridges 35 have a spacingbetween each other to provide contact points 200 with a sufficientdiameter to allow metering device ridges (i.e., metering device ridge35′) of the adjacent metering device (i.e., metering device 10′) to bedisposed therein. Metering device body 30 is rotatable. In embodiments,metering device body 30 rotates with rotation of the attached feedroller 15. In the embodiment of flow measurement device 5 shown in FIG.1, metering device body 30 is attached to roller shaft 25 of feed roller15. Metering device body 30 may be attached to roller shaft 25 by anysuitable method. Metering device attachment plate 240 facilitatesattachment of flow measurement device 5 to feed hopper 180. Forinstance, in an embodiment, flow measurement device 5 is attached tofeed hopper 180 with roller blades 20 of the feed rollers 15 disposedwithin the interior of feed hopper 180 and metering devices 10 disposedoutside of feed hopper 180.

FIG. 3 illustrates a side perspective view of an embodiment of feedroller 15. In such an embodiment, feed roller 15 has roller blades 20,roller shaft 25, and roller shaft shell 40. Roller blades 20 aredisposed on the exterior of feed roller 15 and extend longitudinallyalong the exterior of feed roller 15. Roller blades 20 may have anysuitable configuration to facilitate rotation of feed roller 15. Rollerblades 20 are attached to roller shaft shell 40. Roller blades 20 may beattached to roller shaft shell 40 by any suitable method. In embodimentsas shown, roller blades 20 have sides 205, 210 that extend outward fromroller shaft shell 40 at angles sufficient for sides 205, 210 to contactand form roller blade apex 215 that extends lengthwise along each rollerblade 20. Between each roller blade 20 is a roller blade contact point220. It is to be understood that roller blade contact point 220 is thespace between each roller blade 20. The roller blades 20 have a spacingbetween each other to provide roller blade contact points 220 with asufficient diameter to allow roller blades 20 of the adjacent feedroller 15 to be disposed therein. In an embodiment, roller shaft 25 isattached to roller shaft shell 40 in a sufficient method whereby rollershaft 25 rotates with the rotation of feed roller 15. Roller shaft 25 isdisposed within roller shaft shell 40 with a portion of roller shaft 25extending out of each end of roller shaft shell 40. In alternativeembodiments (not illustrated), feed roller 15 does not have a rollershaft shell 40 but instead the roller blades 20 are attached to theroller shaft 25. It is to be understood that flow measurement device 5is not limited to feed rollers 15, but in alternative embodiments (notillustrated) may include any device suitable for determining the amountof the biomass feedstock fed to pyrolysis and gasification system 175.

FIG. 4 illustrates a side perspective view of an embodiment of airdistribution system 45. Air distribution system 45 has air distributors50 and air distribution plate 55. Air distribution plate 55 providesphysical support to air distributors 50. Air distribution system 45 mayhave any number of air distributors 50 suitable for a desired flow. Inan embodiment as illustrated in FIG. 4, each air distributor 50 has anair distributor base 60 secured to air distribution plate 55. Inembodiments as shown, air distributor base 60 extends vertically fromair distribution plate 55. Air distributor base 60 provides physicalsupport to distribution arm 65. In an embodiment as shown, top portion225 of air distributor base 60 is connected to distribution arm 65 atabout the center of distribution arm 65 (i.e., at connection point 235).In alternative embodiments (not illustrated), top portion 225 isconnected to distribution arm 65 at any suitable location that is not atabout the center of distribution arm 65. As shown, embodiments of airdistributor 50 have distribution arm 65 disposed about perpendicular toair distributor base 60. In alternative embodiments (not illustrated),distribution arm 65 is disposed at any suitable angle to air distributorbase 60. In embodiments, orifices (not illustrated) in air distributionplate 55 allow air to be supplied to the air distributors 50. The airflows through the orifices to air distributor base 60 with the airflowing through air distributor base 60 to distribution arm 65.

FIG. 5 shows a bottom view of an embodiment of an air distributor 50. Asshown, air distributor 50 has distributor entry 75. Distributor entry 75is an air passageway that extends longitudinally through air distributorbase 60. In embodiments, air distributor 50 is sufficiently disposed onair distribution plate 55 so that air distributor base 60 is disposedover an orifice of air distribution plate 55. In embodiments, airdistributor 50 is submerged in bed materials of reactor 185. Airdistributor 50 has distributor orifices 70 through which air flows intothe bed materials and fluidizes the bed. In embodiments, air flows intoair distributor 50 by flowing through an orifice of air distributionplate 55 and into air distributor base 60, with the air flowing throughdistributor entry 75 and into distribution arm 65. The air flows throughdistribution aim 65 and out of air distributor 50 into the reactor bedthrough distributor orifices 70. In an embodiment as shown, distributororifices 70 are disposed on the bottom side 230 of distribution arm 65.Without limitation, the distributor orifices 70 are disposed on thebottom side 230 of distribution arm 65 to facilitate the air inpreventing the bed materials from entering distributor orifices 70 andreducing flow through air distributor 50 or plugging air distributor 50(i.e., plugging the flow of air out of air distributor 50). Airdistributor 50 may have any suitable number of distributor orifices 70for fluidizing the bed materials. In an embodiment, distribution aim 65has the same number of distributor orifices 70 on each side of theconnection point 235 to air distributor base 60. In some embodiments,the distributor orifices 70 have the same spacings between each other.

FIG. 8 illustrates an embodiment of cyclone assembly 140. Cycloneassembly 140 has two cyclones, first cyclone 80 and second cyclone 110.Without limitation, two cyclones (first cyclone 80 and second cyclone110) maximize capture of the solid by-product from pyrolysis andgasification system 175. In alternative embodiments (not illustrated),cyclone assembly 140 has one cyclone or more than two cyclones. In anembodiment, first cyclone 80 is a low energy cyclone, and second cyclone110 is a high efficiency cyclone. It is to be understood that a lowenergy cyclone refers to a cyclone that removes larger particles thatmay impact the performance of high efficiency cyclones on the secondstage. It is also to be understood that a high efficiency cyclone refersto a cyclone that removes the finer char particles to limit particulateemissions. Without limitation, the char is removed prior to the use ofthe syngas to prevent slagging and fouling in downstream conveyingsurfaces. In embodiments as shown, cyclone assembly 140 removes the charfrom the gas (i.e., syngas) exiting reactor 185. Without limitation, thedesign of the cyclones is relevant to the sustainable conversion ofenergy in the biomass feedstock with ash that melts at low temperaturessuch as cattle manure and cotton gin waste materials. in an embodimentas shown in FIGS. 6 and 8, first cyclone 80 has first cyclone body 95with a first cyclone feed arm 90, first cyclone bottom 100, and firstcyclone top 105. First cyclone feed arm 90 has first cyclone feed flange85 by which first cyclone 80 is attached to reactor 185. The gascontaining char exiting reactor 185 flows into cyclone assembly 140 byflowing into first cyclone 80 through cyclone assembly feed 170 of firstcyclone feed arm 90. In first cyclone 80, char is separated from the gaswith the separated char exiting first cyclone 80 through first cyclonebottom 100 and into char collector 190. The gas with remaining charexits first cyclone 80 through first cyclone top 105.

As shown in FIG. 8, first cyclone top 105 is attached to cyclone duct145. The gas exiting first cyclone 80 flows through cyclone duct 145 andinto second cyclone 110. First cyclone top 105 may be attached tocyclone duct 145 by any suitable method. In an embodiment asillustrated, first cyclone top 105 has first cyclone attachment flange155. First cyclone top flange 165 is attached to first cycloneattachment flange 155. First cyclone top flange 165 may be attached tofirst cyclone attachment flange 155 by any suitable method. Withoutlimitation, in embodiments as shown, first cyclone top flange 165facilitates attachment of cyclone duct 145 to first cyclone 80 becausethe opening (not illustrated) at first cyclone top 105 has a widerdiameter than the opening into cyclone duct 145.

As shown in FIGS. 7 and 8, second cyclone 110 is attached to cycloneduct 145. Second cyclone 110 may be attached to cyclone duct 145 by anysuitable method. In an embodiment as shown, second cyclone 110 hassecond cyclone body 125 with a second cyclone feed arm 120, secondcyclone bottom 135, and second cyclone top 130. Second cyclone feed arm120 has second cyclone feed flange 115 by which second cyclone 110 isattached to cyclone duct 145. The gas containing char exiting firstcyclone 80 flows into second cyclone 110 by flowing into second cyclone110 through second cyclone feed arm 120. In second cyclone 110, char isseparated from the gas with the separated char exiting second cyclone110 through second cyclone bottom 135 and into char collector 190. Thegas exits second cyclone 110 through second cyclone top 130.

In embodiments as shown in FIGS. 6-8, first cyclone 80 is a 1D1Dcyclone, which is used to remove the larger char. The following cyclone(second cyclone 110) is a 1D3D cyclone. It is to be understood that 1D1Drefers to a low energy cyclone that removes larger char particles. Inaddition, it is to be understood that 1D3D refers to a high efficiencycyclone that removes the finer char particles. In embodiments, thecut-point of first cyclone 80 is about 6 micrometers aerodynamicequivalent diameter (AED), and the second cyclone 110 cut-point is about3 micrometers AED. It is to be understood that first cyclone 80 andsecond cyclone 110 are not limited to such AED. In some embodiments, thefirst cyclone 80 design is based upon inlet velocities for the 1D1D ofabout 2,400 feet per minute, and the second cyclone 110 is designedbased upon inlet velocities for the 1D3D of about 3,200 feet per minute.It is to be understood that the design inlet velocities are thevelocities that may occur if the gas leaving the gasifier were atstandard temperature and pressure (STP). Without limitation, in anembodiment, an aspect of the first cyclone 80 and second cyclone 110design is the removal of sufficient char prior to burning the cleanedgas in order to minimize slagging and fouling when the low calorificvalue (LCV) gas is burned (i.e., in combustion mode). In alternativeembodiments, first cyclone 80 is a 1D3D cyclone followed by a secondcyclone 110 that is a 1D5D cyclone for particular output char particlesize distributions. In some embodiments, first cyclone 80 and secondcyclone 110 are operated at about the temperature of the gas leavingreactor 185 and are constructed of refractory material. In embodiments(not illustrated), first cyclone 80 and/or second cyclone 110 are fittedwith an air-tight rotary air lock to remove the captured char withoutallowing oxygen to contact the LCV gas. In some embodiments, the char isconveyed by an auger out of the system continuously without affectingoperation.

In an embodiment of operation of pyrolysis and gasification system 175as shown in the embodiments of FIGS. 1-8, biomass feedstock is fed tofeed hopper 180. The biomass feedstock contacts feed rollers 15 of flowmeasurement device 5, which causes feed rollers 15 to rotate when thebiomass feedstock contacts roller blades 20. Rotation of each feedroller 15 rotates the corresponding attached metering device 10. Theamount of feed of biomass feedstock is determined based upon rotation ofthe metering devices 10. The biomass feedstock is fed to reactor 185 bywhich the fluidized bed in the reactor 185 transfers heat to the biomassfeedstock, which converts a portion of the biomass feedstock to syngas.The bed is fluidized by air fed to air distribution system 45. Inembodiments, the air enters air distribution system 45 through orifices(not illustrated) in air distribution plate 55 and from the orifices theair flows into the air distributors 50 and then into the bed. The syngas(which in embodiments includes char) exits reactor 185 and flows tocyclone assembly 140. In cyclone assembly 140, char is removed from thesyngas. The syngas exits second cyclone 110 at second cyclone top 130.The char exits cyclone assembly 140 to char collector 190.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations may be made herein without departing from the spirit andscope of the invention as defined by the appended claims.

What is claimed is:
 1. An air distribution system for a reactor, whereinbed materials are disposed in the reactor, comprising: an airdistribution plate; a plurality of air distributors, wherein theplurality of air distributors are attached to the air distributionplate; wherein each of the air distributors comprises a base and adistribution arm, and wherein the distribution arm comprises distributororifices; and wherein the distribution arm is disposed about parallel tothe air distribution plate, and wherein the distribution arm comprises abottom side, and further wherein the distributor orifices are disposedon the bottom side of the distribution arm.
 2. The air distributionsystem of claim 1, wherein the air distribution system provides air tothe bed materials to provide a fluidized bed in the reactor.
 3. The airdistribution system of claim 2, wherein the air distribution system issubmerged in the fluidized bed.
 4. The air distribution system of claim1, wherein the reactor is disposed in a gasifier for producing asynthesis gas and bio-char from a biomass feedstock.
 5. The airdistribution system of claim 1, wherein the distribution arm is disposedabout perpendicular to the base.
 6. The air distribution system of claim1, wherein air flows from the base to the distribution arm.
 7. A flowmeasurement device adapted for measuring biomass flow, comprising: aplurality of feed rollers, wherein each of the feed rollers isrotatable, and wherein each feed roller comprises a roller shaft androller blades; and wherein the flow measurement device is calibrated toallow determination of the biomass flow from rotation of the feedrollers.
 8. The flow measurement device of claim 7, wherein the rollerblades of a feed roller contact the roller blades of an adjacent feedroller when one or both of the feed rollers are rotating.
 9. The flowmeasurement device of claim 7, further comprising a metering deviceattached to each feed roller.
 10. The flow measurement device of claim9, wherein rotation of each feed roller rotates the attached meteringdevice.
 11. The flow measurement device of claim 9, wherein the meteringdevice comprises metering device ridges and contact points disposedbetween each adjacent metering device ridge.
 12. The flow measurementdevice of claim 11, wherein a metering device ridge is disposed in thecontact point of an adjacent metering device.
 13. The flow measurementdevice of claim 9, wherein each metering device rotates with rotation ofan adjacent metering device.
 14. A cyclone assembly for removing charfrom a gas produced from a biomass feedstock, comprising: a firstcyclone, wherein the first cyclone is a low energy cyclone; a secondcyclone, wherein the second cyclone is a high efficiency cyclone; andwherein the first cyclone is disposed to receive the gas, and whereinthe gas exiting the first cyclone flows to the second cyclone.
 15. Thecyclone assembly of claim 14, wherein the gas comprises a temperature,and wherein the first cyclone and the second cyclone are operated atabout the temperature of the gas.
 16. The cyclone assembly of claim 14,wherein the gas flows to the second cyclone through a cyclone duct. 17.The cyclone assembly of claim 14, wherein the first cyclone is a 1D1Dcyclone, and wherein the second cyclone is a 1D3D cyclone.
 18. Thecyclone assembly of claim 14, wherein the first cyclone is a 1D3Dcyclone, and wherein the second cyclone is a 1D5D cyclone.
 19. Thecyclone assembly of claim 14, wherein the first cyclone and/or thesecond cyclone comprise a rotary air lock.
 20. The cyclone assembly ofclaim 14, wherein the first cyclone comprises a cut-point of about 6micrometers aerodynamic equivalent diameter, and the second cyclonecomprises a cut-point of about 3 micrometers aerodynamic equivalentdiameter.